Because of the progressiveness of micro-electromechanical techniques, the demands for miniature flow meter are increased day by day over the market, for example, to control a reagent at the aspect of biotechnology-medical or to be a blood-injecting pump meter etc. However, with the current techniques, the commercial miniature flow meter seldom provides a sufficient calibration method in accordance with the international standard for the flow measuring capability thereof. Hence the users cannot insure the reliability of measured data by the miniature flow meter.
Currently, only a few feasible miniature flow meters are available on the market. The metering principles thereof are categorized into two classifications as follows: thermal sensing type and pressure gradient type. The Sensirion SLG1430-025 developed by the Swiss trade, and the Thermal Flow Sensor developed by Dr. Tai, CIT are the well-known representatives of thermal sensing type miniature flow meter. The metering capabilities of both types are declared in the range from 50 nL/min to 1500 nL/min, but the maximum error of thermal sensing type miniature flow meter is up to 10%. The Miniature Flow Sensor developed by U.S. trade Seyonic is the well-known representative of pressure gradient type miniature flow meter. The minimum metering capability of pressure gradient type miniature flow meter approximates to around 300 μL/min. Nevertheless, up to the present, the aforementioned pressure gradient type miniature flow meter is still in the stage of experimental product.
With respect to the aspect of calibration method, it is not provided by the majority of the miniature flow meter products. The minority suchlike Dr. Tai, CIT provides some reference material explaining that the calibration method they adopted is by the following: a graduated syringe is connected to the end of the miniature flow meter, whereby a reading is readout for judging the accuracy of the instant flow rate. Because the aforementioned metering method bears errors due to the subjective presumption thereof, this calibrating method is generally considered insufficient.
In the case of Taiwan, Center for Measurement Standards, Industrial Technology Research Institute is one of the research institutes devoted to the field of micro flow measuring technique thereof, which center has devoted to develop the micro flow measuring standards since three years ago. Up to the present, the prototype technique using gravimetric method has been developed. However, since the gravimetric method is restricted by many external surroundings (such as the evaporation, the variation of the temperature/humidity etc.), the minimum measurable flow thereof barely comes to the level about 1 μL/min. Moreover, the micro flow measuring system configured with the gravimetric method is bulky and requires a highly stable condition for the external surroundings. Hence the system thereof is not feasible for the ordinary commercial usage, and is obviously not convenient enough.
To overcome the aforementioned drawbacks of the prior art, a novel device for measuring flow and the method manufacturing the novel device thereof is provided.